Low temperature spray drying of carrier-free compositions

ABSTRACT

A spray drying process and apparatus for drying a spray dryable liquid composition to a spray dried powder is described, in which the spray dryable liquid composition contains no carrier. The spray dryable liquid composition is processed at a solids concentration not exceeding 80% by weight, based on total weight of the spray dryable liquid composition, being atomized to generate an atomized spray of liquid particles of the spray dryable liquid composition into a spray drying chamber, in which the atomized spray is contacted with a stream of drying fluid flowed at temperature not exceeding 100° C. into the spray drying chamber, to form the spray dried powder.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation under 35 USC § 120 of U.S. patent applicationSer. No. 16/800,961 filed Feb. 25, 2020 in the names of Charles PershingBeetz, Jason Andrew Beetz, Daniel Michael Schlipf, and Jason Zhixin Lifor LOW TEMPERATURE SPRAY DRYING OF CARRIER-FREE COMPOSITIONS, now U.S.Pat. No. 10,850,244, which in turn is a continuation under 35 USC § 120of U.S. patent application Ser. No. 15/965,910 filed Apr. 28, 2018 inthe names of Charles Pershing Beetz, Jason Andrew Beetz, Daniel MichaelSchlipf, and Jason Zhixin Li for LOW TEMPERATURE SPRAY DRYING OFCARRIER-FREE COMPOSITIONS, now U.S. Pat. No. 10,569,244. The disclosuresof U.S. patent application Ser. Nos. 15/965,910 and 16/800,961 arehereby incorporated herein by reference, in their respective entireties,for all purposes.

BACKGROUND Field of the Disclosure

The disclosure relates to low temperature spray drying in carrier-freecompositions are spray dried to a spray dried powder, and has particularutility to the processing of thermally sensitive materials.

Description of the Related Art

Spray drying has existed as a basic materials processing operation sincethe late 1800s, and has been continually refined since that time. Thespray drying operation may be of varied character, but typicallyinvolves injecting a liquid composition of material into a chamber forcontact with a drying fluid concurrently flowed through the chamber. Theinjected wet material in the form of droplets contacts the stream ofdrying fluid so that the liquid passes from the droplets to the dryingfluid stream, producing a spray dried product that is discharged fromthe drying chamber, and drying fluid effluent that likewise isdischarged from the drying chamber.

In prior spray drying operations, it has been conventional practice toprovide the drying fluid as a gas at high elevated temperature, e.g.,temperatures on the order of 180-200° C., in order to produce dry powderproducts. The drying fluid has conventionally been air, and the materialto be spray dried may be provided in a dryable liquid form, e.g., as aneat liquid material, or the material may be a solid in a spray dryingliquid composition of slurry, suspension, emulsion, or solution form,which may additionally include carrier material with which the spraydried product is associated at the conclusion of the spray dryingprocess. In various applications, the material to be spray dried ispresent in a slurry containing solvent, e.g., water, alcohol, or otherappropriate liquid, as well as a carrier material, such as carbohydrate,cellulosic, wax, gum, protein, or other suitable material. To effect thespray drying operation, the spray drying composition is injected intothe drying chamber using a nozzle, atomizer, or the like, to form aspray of fine droplets for contacting with the drying fluid that isflowed into and through the drying chamber.

The aforementioned high elevated temperature levels on the order of180-200° C. for the drying fluid have been conventional practice in theart, in order to rapidly heat the droplets of spray dried material andvolatilize the liquid therefrom for production of spray dried powder.Such high temperature levels, however, limit the applicability of thespray drying operation to spray dryable materials that are thermallystable or otherwise are not severely adversely affected at the hightemperatures of the spray drying operation. A wide variety of materialscan accommodate the high temperature regime of the spray dryingoperation, but suffer losses of material (through volatilization of theproduct material at high temperature) and/or otherwise are degraded inphysical properties and/or performance characteristics as a result oftheir high temperature exposure during the spray drying operation. Insuch respect, the conventional spray drying practice has recognizedlimitations and deficiencies.

Against the foregoing context, the low temperature spray dryingapparatus and process disclosed in ZoomEssence, Inc.'s U.S. Pat. Nos.8,939,388, 9,332,776, and 9,551,527 embody a substantial advance in theart involving starch carriers. As disclosed in such patents, spraydrying is carried out at spray drying conditions including inlettemperature of the drying fluid below 100° C., and even down to ambienttemperature in some applications, utilizing spray drying slurriesincluding starch carrier, active ingredient, and solvent, in which theslurry has viscosity above about 300 mPa-sec, slurry water content notexceeding 50% by weight of the slurry, and low humidity of the dryingfluid introduced to the drying system. Such starch-based slurry spraydrying operation, conducted at low temperature spray drying conditionsmarkedly different from the conventional practice of the art, enablesspray drying to be utilized for a myriad of products that wouldotherwise be contraindicated by the elevated temperature conditions ofconventional high temperature spray drying practice.

There exist, however, a large population of materials that is notamenable to starch-based slurry spray drying.

SUMMARY

The present disclosure relates to spray drying of carrier-freecompositions at low temperature.

As discussed in the Background section hereof, U.S. Pat. Nos. 8,939,388,9,332,776, and 9,551,527 embody a substantial advance in the artinvolving spray drying of slurries containing starch carrier, activeingredient, and solvent, to produce spray dried active ingredientsencapsulated by the starch carrier. Starch carrier slurries processed byspray drying involve substantial amounts of starch in the spray dryablefeedstock

A priori, it is not evident that a corresponding low temperature processcould be effectively utilized to achieve spray dried powder products ofthe superior character that have been found to be achievable where nocarrier is present, without hydrodynamic enhancement in the spray dryingchamber or the provision of excessively long residence times in thespray drying chamber, since active ingredients are not supported by thepresence of carriers in the formation of particles and therefore must bedried to even higher standards of solvent minimization.

It has been surprisingly and unexpectedly found, however, that lowtemperature spray drying can be effectuated in a remarkably effectivemanner, when the spray drying process is carried out with a carrier-freefeedstock of the active ingredient and solvent, in which the dryingfluid, which may for example be air, nitrogen, oxygen, helium, argon,carbon dioxide, or other suitable gas or gas mixture, is introduced to aspray drying chamber at a drying fluid temperature T (° C.) notexceeding 100° C., to achieve spray dried powder products of theaforementioned superior character.

In one aspect, the present disclosure relates to a spray drying processfor drying a spray dryable liquid composition to a spray dried powder,wherein the spray dryable liquid composition contains no carrier, theprocess comprising:

providing the spray dryable liquid composition at a solids concentrationnot exceeding 80% by weight, based on total weight of the spray dryableliquid composition;

atomizing the spray dryable liquid composition to generate an atomizedspray of liquid particles of the spray dryable liquid composition into aspray drying chamber;

flowing a stream of drying fluid at temperature not exceeding 100° C.into the spray drying chamber for flow through the spray drying chamber,to contact the spray of liquid particles therein for drying of theliquid particles to form the spray dried powder; and

discharging from the spray drying chamber effluent drying fluid and thespray dried powder dried by contact with the drying fluid in the spraydrying chamber.

In another aspect, the disclosure relates to a spray drying systemconstructed and arranged to carry out the above-described carrier-freespray drying process.

Other aspects, features and embodiments of the disclosure will be morefully apparent from the ensuing description and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a spray drying process systemaccording to one embodiment of the present disclosure.

DETAILED DESCRIPTION

The present disclosure relates to low temperature (≤100° C.) spraydrying of carrier-free spray dryable liquid compositions to form a spraydried powder.

As used herein, the term “carrier” refers to a solid material that isutilized in a spray dryable liquid composition, containing liquid andthe product to be spray dried, to carry and at least partially supportor at least partially encapsulate the product in the spray dried powderresulting from the spray drying operation. Carriers thus may beassociated with the product material in spray dried powders, e.g., as asubstrate, support, or associative matrix for the product material.Carriers used in spray drying operations may be of widely varying types,and may include, for example, the starch carriers disclosed in theaforementioned U.S. Pat. Nos. 8,939,388, 9,332,776, and 9,551,527. Moregenerally, carriers such as those listed in Table 1 below illustratespecific carrier materials.

TABLE 1 Spray Drying Carriers Polysaccharides: starches, modified foodstarches, native starches, maltodextrins, alginates, pectins,methylcellulose, ethylcellulose, hydrocolloids, inulin, carbohydrates,mono-, di- and tri-saccharides, soluble fibers, polydextrose Proteins:animal proteins, plant proteins, caseinates, gelatins, soy proteins, peaproteins, whey proteins, milk proteins Gums: guar gum, xanthan gum,acacia gum (gum arabic), gellan gum, and caragenan Esters: Polysorbates,stearic acid esters, oleic acid esters Lipids and waxes: coconut oil,medium chain triglyceride (MCT) oils, vegetable oils, sunflower oils,palm oils, caruba waxes, bee waxes

As used herein, the term “carrier-free” in reference to a spray dryableliquid composition means a spray dryable liquid composition that isdevoid of a carrier therein, and “carrier-free” in reference to a spraydrying process means a spray drying process carried out in the absenceof a carrier in the spray drying operation.

In one aspect, the present disclosure relates to a spray drying processfor drying a spray dryable liquid composition to a spray dried powder,wherein the spray dryable liquid composition contains no carrier, theprocess comprising:

providing the spray dryable liquid composition at a solids concentrationnot exceeding 80% by weight, based on total weight of the spray dryableliquid composition;

atomizing the spray dryable liquid composition to generate an atomizedspray of liquid particles of the spray dryable liquid composition into aspray drying chamber;

flowing a stream of drying fluid at temperature not exceeding 100° C.into the spray drying chamber for flow through the spray drying chamber,to contact the spray of liquid particles therein for drying of theliquid particles to form the spray dried powder; and

discharging from the spray drying chamber effluent drying fluid and thespray dried powder dried by contact with the drying fluid in the spraydrying chamber.

The spray drying processes of the present disclosure may be carried outwith carrier-free spray dryable liquid compositions containing any of avariety of product materials, e.g., at least one product materialselected from the group consisting of food materials, beveragematerials, fragrance materials, pigment materials, flavor materials,pharmaceutical materials, therapeutic materials, medication materials,homeopathic materials, biological materials, probiotic materials,construction materials, formulating materials, and mixtures, blends,composites, and combinations of two or more different materials of theforegoing.

Specific product materials in the spray dryable liquid composition mayfor example include at least one product material selected from thegroup consisting of apple juice, tea, coffee, pear juice, amino acids,fruit purées, pectin, beef broths, gelatin, pharmaceutical products,beet juice, grape juice, pineapple juice, betacyclodextran, lime juice,skim milk, carrageenan, liquid egg, sugars, cheese whey, beers, lowalcohol beer, vegetable juices, chicken broth, mango juice, wheyprotein, citrus juice, orange juice, and whole milk.

In specific embodiments, the spray dryable liquid composition maycomprise a juice. In other embodiments, the spray dryable liquidcomposition may comprise an alcoholic spirit, mash mixture, or potliquor. In still other embodiments, the spray dryable liquid compositionmay comprise a comestible or beverage or a precursor thereof. In variousother embodiments, the spray dryable liquid composition may comprisecoffee. In yet other embodiments, the spray dryable liquid compositionmay comprise tea.

The carrier-free spray dryable liquid compositions in the broad practiceof the present disclosure may comprise any additional non-carrieringredients, in addition to the product material and liquid. Suchadditional non-carrier ingredients may include adjuvants, excipients,surfactants, anti-agglomerating agents, anti-caking agents, coactiveingredients, wetting agents, dispersants, emulsifiers, stabilizers,antioxidants, preservatives, poor-forming agents, hardeners, andmixtures, blends, composites, and combinations of two or moreingredients of such types.

The spray dried powder that is produced by the spray drying process andapparatus of the present disclosure may be in any suitable morphologicaland physical forms, including spherical, spheroidal, polygonal,cuboidal, rod, fiber, helical, dendritic, and any other spatial forms,and may be of any suitable particle size distribution appropriate to thespray dried powder.

The process of the present disclosure as broadly specified aboveinvolves flowing a stream of drying fluid at temperature not exceeding100° C. into the spray drying chamber for flow through the spray dryingchamber, to contact the spray of liquid particles therein for drying ofthe liquid particles to form the spray dried powder. It will beappreciated that in specific implementations of such process, thetemperature of the drying fluid stream flowed into the spray dryingchamber may be widely varied within such maximum temperatureconstraints. For example, the temperature of the stream of drying fluidflowed into the spray drying chamber may in various embodiments be belowat least one of 100° C., 99° C., 98° C., 95° C., 90° C., 85° C., 80° C.,75° C., 70° C., 65° C., 60° C., 55° C., 50° C., 45° C., 40° C., 30° C.,25° C., 22° C., 20° C., 18° C., 16° C., 15° C., 14° C., 13° C., 12° C.,11° C., and 10° C., and such temperature is above freezing point of theliquid in the spray dryable liquid composition.

In various embodiments, the temperature of the stream of drying fluidflowed into the spray drying chamber may be in a range in which thelower end point of the range is any one of 0° C., 1° C., 2° C., 3° C.,4° C., 5° C., 6° C., 7° C., 8° C., 9° C., 10° C., 11° C., 12° C., 13°C., 14° C., 15° C., 16° C., 18° C., 20° C., 22° C., and 25° C., and inwhich the upper end point of the range is greater than the lower endpoint of the range, and is any one of 10° C., 11° C., 12° C., 13° C.,14° C., 15° C., 16° C., 18° C., 20° C., 22° C., 25° C., 30° C., 40° C.,45° C., 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C.,90° C., 95° C., 98° C., 99° C., or 100° C. for example, the temperatureof the stream of drying fluid flowed into the spray drying chamber maybe in a range of 1° C. to 95° C., 5° C. to 90° C., 10° C. to 80° C., or15° C. to 65° C., in particular applications.

In the process of the present disclosure as variously described herein,the stream of drying fluid flowed into the spray drying chamber may havea relative humidity that is at or below a predetermined level for thespecific application. In various embodiments, the stream of drying fluidflowed into the spray drying chamber may have a relative humidity thatdoes not exceed 35%, 30%, 25%, 20%, 15%, 12%, 10%, 8%, 6%, 5%, 4%, 3%,2.5%, 2%, 1.8%, 1.6%, 1.5%, 1.4%, 1.3%, 1.2%, 1.1%, 1.0%, 0.9%, 0.8%,0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1%, 0.05%, 0.02%, or 0.01%.

In various embodiments, the relative humidity of the stream of dryingfluid flowed into the spray drying chamber may be in a range in whichthe lower end point of the range is any one of 10⁻⁴%, 10⁻³%, 10⁻⁴%,10⁻¹%, 1%, 1.5%, or 2%, and in which the upper end point of the range isgreater than the lower end point of the range, and is any one of 35%,30%, 20%, 15%, 12%, 10%, 8%, 6%, 5%, 4%, 3%, 2.5%, 2%, 1.8%, 1.6%, 1.5%,1.4%, 1.3%, 1.2%, 1.1%, 1.0%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%,0.2%, 0.1%, 0.05%, 0.02%, 0.01%, or 0.05%. For example, the stream ofdrying fluid flowed into the spray drying chamber has a relativehumidity in a range of 10⁻¹% to 35%, 10⁻³% to 18%, 0.005 to 17%, 0.01%to 15%, 0.01 to 5%, 0.1 to 5%, or 0.001% to 2%.

The drying fluid in the practice of the process of the presentdisclosure may be of any suitable type, and may for example comprise gasselected from the group consisting of air, oxygen, oxygen-enriched air,nitrogen, helium, noble gases, carbon dioxide, carbon monoxide, andcombinations of two or more of the foregoing. For example, the dryingfluid may comprise oxygen, oxygen-enriched air, nitrogen, helium, argon,neon, carbon dioxide, carbon monoxide, or other fluid species, includingsingle component fluids, as well as fluid mixtures. The drying fluid mayin various applications exist in a gaseous or vapor form, and the fluidshould be constituted to provide an appropriate mass transfer drivingforce for passage of solvent or other desirably volatilizable materialfrom the atomized sprayed droplets to the drying fluid.

The liquid in the spray dryable liquid composition may likewise be ofany suitable type and may for example comprise liquid selected from thegroup consisting of consisting of water, inorganic solvents, organicsolvents, and combinations thereof. In various embodiments, organicsolvents may be employed, such as for example acetone, chloroform,methanol, methylene chloride, ethanol, dimethyl formamide (DMF),dimethyl sulfoxide (DMS), glycerine, ethyl acetate, n-butyl acetate, andmixtures with water of the one or more of the foregoing. Such organicsolvents may for example be used in spray drying of spray dryablecompositions including protein-based materials. In specific embodiments,solvent selected from the group consisting of water, alcohols, andwater-alcohol solutions may be advantageously employed.

Spray dryable liquid compositions in the practice of the spray dryingprocess variously described herein may have any suitable physicochemicalproperties appropriate to the spray drying operation involving theparticular material being spray dried. By way of example, the spraydryable liquid composition may have a viscosity in a range of from 50mPa-s to 28,000 mPa-s.

In various embodiments, the spray dryable liquid composition may have aviscosity that is in a range in which a lower limit of the range is anyone of 325, 340, 350, 375, 400, 450, 500, 550, 600, 650, 700, 750, 800,850, 900, 950, and 1000 mPa-s, and in which an upper limit of the rangeis greater than the lower limit and is any one of 400, 450, 500, 550,600, 650, 700, 750, 800, 850, 900, 950, 1000, 2000, 3000, 4000, 5000,6000, 7000, 8000, 9000, 10,000, 11,000, 12,000, 13,000, 14,000, 15,000,16,000, 17,000, 18,000, 19,000, and 20,000 mPa-s. As a further specificexample, the spray dryable liquid composition may have a viscosity in arange of from 50 to 5000 mPa-s. Viscosity values may be determined inspecific applications and implementations using any suitableviscosity-determination methods and viscometry equipment, such asviscometers and rheometers of appropriate types.

It will therefore be appreciated that the viscosity of the spray dryableliquid composition in the spray drying processes of the presentdisclosure may be widely varied, depending on the specific productmaterial, liquid, and spray drying apparatus employed, as well as thesolids concentration in the spray dryable liquid composition. Spraydryable liquid compositions of any suitable solids concentrationcharacter may be employed. In various embodiments, the spray dryableliquid composition may have a solids concentration in a range of from45% to 75% by weight, based on total weight of the spray dryable liquidcomposition. In other embodiments, the spray dryable liquid compositionmay have a solids concentration in a range of from 50% to 70% by weight,based on total weight of the spray dryable liquid composition.

In order to enhance the spray drying operation involving thecarrier-free spray dryable liquid composition, it may be advantageous invarious implementations to generate localized turbulence at multipleloci in the spray drying chamber, to achieve highly efficient drying ofthe spray dryable liquid composition in the spray drying chamber. Suchlocalized turbulence may be generated by injection of secondary dryingfluid into the spray drying chamber, e.g., from injection jetspositioned at corresponding openings in the wall of the spray dryingchamber, and/or interiorly in the spray drying chamber, to provideenhancement of mass transfer and diffusivity in relation tovolatilization of liquid from the sprayed atomized droplets of the spraydryable liquid composition.

As another option that may be useful to enhance spray drying operation,the spray drying process in various embodiments as described herein mayfurther comprise applying an electrohydrodynamic charge (typicallyreferred to misnomerically as electrostatic charge, with correspondingspray drying commonly referred to as electrostatic spray drying) to atleast one of the spray dryable liquid composition and the atomized sprayof liquid particles, for electrohydrodynamic spray drying of the spraydryable liquid composition. Such electrohydrodynamic spraying operationmay be carried out at any suitable voltage conditions appropriate to thespecific application in which electrohydrodynamic spraying is employed.In various embodiments, the electrohydrodynamic charge may be in a rangeof from 0.25 to 80 kV although it will be appreciated that higher orlower electrohydrodynamic charge may be imparted to the material to bespray dried in specific applications. In various embodiments,electrohydrodynamic charge imparted to the particles being spray driedmay be in a range of from 0.5 to 75 kV, or from 5 to 60 kV, or from 10to 50 kV, or in other suitable range or other specific value.

In other embodiments of electrohydrodynamic spray drying conducted inaccordance with the present disclosure, the feedstock liquid compositionmay be sprayed through an electrohydrodynamic nozzle operatively coupledwith a voltage source arranged to apply a cyclically switched voltage tothe nozzle, e.g., between high and low voltages that are within any ofthe above-discussed, or other, voltage ranges.

Post atomization charging of the spray dryable composition droplets maybe carried out with corona discharge-type atomizers which use anexternal electrode with the nozzle grounded, or, if the conductivitycharacteristics of the spray dryable composition droplets are favorable,such post atomization charging may be carried out with electron beamirradiation of the atomized droplets.

Thus, electrohydrodynamic charging of the spray dryable liquidcomposition may be carried out before, during, or after atomization ofsuch composition. Electrohydrodynamic spraying equipment of widelyvarying types may be utilized in electrohydrodynamic spraying systemsand operations in accordance with the present disclosure, e.g., anelectrohydrodynamic spraying device positioned to introduce anelectrohydrodynamically charged spray of the spray dryable liquidcomposition into the interior volume of a spray drying vessel forcontacting with drying fluid therein.

The spray dryable liquid composition constituting the feedstock to thespray drying system may be the product of an upstream processingoperation, in which a feedstock precursor composition may be processedto provide the spray dryable liquid composition of appropriate orotherwise desired character. In various embodiments, the upstreamprocessing operation may concentrate the feedstock precursor compositionso that it has a higher concentration of the product material in aliquid than the concentration of the product material in the feedstockprecursor composition. For this purpose, any suitable concentrationmethod and apparatus may be employed. Examples of suitable concentrationtechniques and apparatus that may be employed include forward osmosis,reverse osmosis, frame and plate heat exchangers, evaporators, spinningcones, osmosis evaporation, chromatography, filtration, nanofiltration,distillation, crystallization, vacuum separation, absorption, andadsorption, as well as suitable combinations of two or more of theforegoing.

Correspondingly, the spray dried powder produced by the carrier-freespray drying process of the present disclosure may be further treated bya downstream treatment process of suitable type, e.g., for furtherdrying, development of performance characteristics (such as flavor,taste, or aroma characteristics in the case of flavor spray driedpowders, for example), mixing with other powder ingredients to formend-product powder mixtures, granulation, micronizing, or other sizingor morphological processing, lyophilization, dispersion, blending,irradiation, and/or a wide variety of other downstream processingoperations to produce an intermediate or end-use product for an intendedapplication or field of use.

The effluent drying fluid that is discharged from the spray dryingchamber in the carrier-free spray drying process of the presentdisclosure may correspondingly be further treated or processed. Invarious embodiments, the effluent drying fluid discharged from the spraydrying chamber is treated to remove solids therefrom to producesolids-depleted drying fluid, and the solids-depleted drying fluid isrecycled as drying fluid in the stream of drying fluid flowed into thespray drying chamber. The effluent drying fluid may additionally oralternatively be treated or processed in the spray drying system torender it of appropriate character for other uses outside the spraydrying system and operation, or for effluent discharge to the ambientenvironment of the spray drying system or to the atmosphere.

In various embodiments, the effluent drying fluid discharged from thespray drying chamber is treated to remove solids therefrom in a cycloneseparator or other solids-fluid separator followed by flow of theeffluent drying fluid through a bag filter or other filter assembly orfilter medium to produce the solids-depleted drying fluid of desiredcharacter for recycle and/or ultimate discharge.

When recycled to the spray drying chamber for flow therethrough, thesolids-depleted drying fluid may be treated to adjust thecharacteristics thereof, e.g., temperature and/or relative humiditycharacteristics.

The spray dried powder produced by the carrier-free spray drying processmay be dried to any suitable powder characteristics. For example, invarious embodiments, the spray drying process may be conducted in thespray drying system to produce spray dried powder discharged from thespray drying chamber in which the amount of liquid in the spray driedpowder discharged from the spray drying chamber is below at least one of10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5 and 0.1 wt. % liquid, based on totalweight of the spray dried powder. In various embodiments, the spraydrying process may be carried out and the spray drying system may beoperated, to produce spray dried powder discharged from the spray dryingchamber having liquid content in a predetermined range, e.g., in a rangeof 5-8 wt. %, 2-3 wt. %, 4-6 wt. %, 5-10 wt. %, based on total weight ofthe spray dried powder, or liquid content in some other range or subjectto some other predetermined maximum liquid content value. The spraydried powder produced in the practice of the present disclosure is ofmarkedly superior character, as regards its powder characteristics andperformance characteristics, which in specific instances may includecharacteristics such as flavor, taste, aroma, solubility, agglomerationresistance, stability, oxidation resistance, degradation resistance,integrity of active product ingredient(s), processability, etc.

In the broad practice of the present disclosure, the apparatus that isutilized to atomize the spray dryable liquid composition to generate anatomized spray of liquid particles of the spray dryable liquidcomposition into a spray drying chamber may be of any suitable type, andmay for example comprise a rotary atomizer, centrifugal atomizer,nebulizer, ultrasonic disperser, nozzle, or a combination of two or moreof the foregoing. The liquid composition may be introduced into theinterior volume of the spray drying vessel in a liquid film or ligamentform that is broken up to form droplets. A wide variety of equipment andtechniques is able to be utilized to form the spray of liquidcomposition in the form of droplets or finely divided liquid particles.Typically, droplet size and distribution may be fairly constant for agiven spray drying technique, and in various embodiments may be in arange of 10-300 μm, or other suitable range.

In another aspect, the disclosure relates to a spray drying systemconstructed and arranged to carry out the carrier-free spray dryingprocess variously described hereinabove.

The spray drying system is shown in an illustrative implementation inFIG. 1 hereof.

As shown, the spray drying system 500 includes a feedstock precursorcomposition source 502, from which which a feedstock precursorcomposition is flowed in feed line 504 to a feedstock compositionprocessing unit 506, in which the precursor composition is processed toyield the spray dryable liquid composition. Such upstream processingunit may be of any suitable type as previously discussed herein, and mayfor example comprise a concentration unit in which the product materialto be spray dried is concentrated from a feedstock precursor compositionconcentration to a higher product material concentration in the spraydryable liquid composition discharged from the unit in line 508.

From the feedstock composition processing unit 506, the carrier-freespray dryable liquid composition is flowed in liquid composition feedline 508 by pump 510 to feedstock feed line 512, from which it flowsinto the spray dryer inlet 516 of the spray dryer vessel 518, andthereupon is atomized by the atomizer 514 to generate an atomized spray520 of the spray dryable liquid composition. Concurrently, conditioneddrying fluid described more fully hereinafter is flowed in conditioneddrying fluid feed line 570 to the inlet 516 of the spray dryer vessel518, so that the introduced conditioned drying fluid flows through theinterior volume 522 of the spray dryer vessel 518, for contact with theatomized spray of carrier-free spray dryable liquid composition.

The conditioned drying fluid, or any portion thereof, may be flowedthrough the atomizer 514, in a so-called two-fluid atomization, or theconditioned drying fluid may be flowed into the interior volume 522 ofthe spray drying vessel 518 as a separate stream, in relation to theintroduction of the carrier-free spray dryable liquid composition andits passage through the atomizer 514.

The atomizer 514 may be of any suitable type, and may for exampleinclude any of rotary atomizers, centrifugal atomizers, jet nozzleatomizers, nebulizers, ultrasonic atomizers, etc., and combinations oftwo or more of the foregoing. The atomizer may be electrohydrodynamic tocarry out electrohydrodynamic spray drying of the concentrated feedstockcomposition, or the atomizer may be non-electrohydrodynamic incharacter.

Regardless of the specific atomizer type and mode of atomizationemployed, the atomized spray 520 of concentrated feedstock compositionis introduced to the interior volume 522 of the spray drying vessel 518,and the atomized droplets of the carrier-free spray dryable liquidcomposition are contacted with the conditioned drying fluid during theirpassage through the interior volume to the spray dryer outlet 524, todry the atomized droplets and produce the spray dried dry powderproduct.

The spray drying vessel 518 may optionally be provided with auxiliarydrying fluid peripheral feed lines 526, in which the arrowheads of therespective schematic feed lines 526 designate injector jets arranged tointroduce auxiliary drying fluid into the interior volume 522 of thespray drying vessel 518. The feed lines 526 and injector jets thereofthus may pass through corresponding wall openings in the spray dryingvessel 518 so that the injector jets are internally arrayed, or theinjector jets may be arranged so that they communicate with wallopenings in the spray drying vessel, injecting auxiliary drying fluidtherethrough into the interior volume 522. The auxiliary drying fluidmay be introduced into the interior volume of the spray drying vessel atsufficient pressure and flow rate to generate localized turbulence 530at or near the point of introduction into the interior volume of thespray drying vessel.

The auxiliary drying fluid peripheral feed lines 526 are illustrated asbeing coupled with an auxiliary drying fluid manifold 528 through whichthe auxiliary drying fluid is flowed to the respective feed lines 526.The auxiliary drying fluid may be introduced into the interior volume ofthe spray drying vessel in a continuous manner, or in an intermittentmanner. The auxiliary drying fluid may be introduced in bursts, e.g., ina time-sequenced manner, and the injector jets may be programmablyarranged under the monitoring and control of a central processor unitsuch as the CPU 590 illustrated in FIG. 1.

Such localized induction of turbulence is highly effective in enhancingthe diffusivity and mass transfer of liquid from the atomized dropletsof concentrated feedstock composition to the drying fluid present in thespray drying vessel.

The spray drying vessel 518, as a further enhancement of the drying ofthe atomized droplets of concentrated feedstock composition in theinterior volume of the vessel, may be equipped with an auxiliary dryingfluid central feed line 532 as shown. The auxiliary drying fluid centralfeed line 532 is provided with a series of longitudinally spaced-apartauxiliary drying fluid central feed line injector jets 534, in whichauxiliary drying fluid may be injected under sufficient pressure andflow rate conditions to generate auxiliary drying fluid injectedturbulence regions 536.

As discussed above with respect to the auxiliary drying fluid introducedinto the interior volume of the spray drying vessel through the feedlines 526 and associated injector jets, the auxiliary drying fluid maybe introduced into the interior volume of the spray drying vessel in acontinuous manner, or in an intermittent manner from the injector jets534, to provide auxiliary drying fluid injected turbulence regions 536at a central portion of the interior volume 522 in the spray dryingvessel. As discussed in connection with the peripheral feed lines andassociated injector jets, the auxiliary drying fluid may be introducedthrough the central feed line injector jets 534 in bursts, e.g., in atime-sequenced manner, and the injector jets may be programmablyarranged under the monitoring and control of a central processor unitsuch as the CPU 590 illustrated in FIG. 1.

A combination of peripheral jets and central jets such as shown in FIG.1 may be used to provide localized turbulence in the central region aswell as the outer wall region of the interior volume in the spray dryervessel, and effects a remarkably efficient spray drying process, inwhich anomalous flow behavior, such as dead zones or stagnant regions inthe interior volume, is minimized. A highly favorable hydrodynamic masstransfer environment is correspondingly provided, and the spray dryervessel as a result of such localized turbulence generation capabilitycan be substantially reduced in size and associated footprint, therebyenabling smaller pumps, compressors, blowers and other associatedancillary equipment to be employed, with consequent enhancement of thecapital equipment and operating cost characteristics of theconcentration and spray drying system.

The spray dried powder and effluent drying gas that are produced by thecontacting of the atomized droplets of concentrated feedstockcomposition with drying fluid in the interior volume of the spray dryervessel, are discharged from the spray dryer vessel in spray dryer outlet524 and flow in spray dryer effluent line 538 to cyclone 540. In lieu ofcyclone equipment, any other suitable solids/gas separation unit ofappropriate character may be employed. The cyclone 540 separates driedsolids from the drying fluid, with the dried solids flowing in driedsolids discharge line 542 to a dried solids collection vessel 544. Thedrying fluid depleted in solids content flows from the cyclone in dryingfluid discharge line 546, flowing through fines filter 548 to condenser550. In the condenser 550, the drying fluid is cooled, resulting incondensation of condensable gas therein, with condensate beingdischarged from the condenser in condensate discharge line 552.

The resulting condensate-depleted drying fluid then flows in dryingfluid recycle line 554 containing pump 556 therein to the drying fluidconditioning assembly 568, together with any needed make-up drying fluidintroduced in drying fluid make-up feed line 610. The drying fluidconditioning assembly conditions the recycle drying fluid and any addedmake-up drying fluid for flow to the spray dryer vessel 518 inconditioned drying fluid feed line 570. The drying fluid conditioningassembly may comprise a dehumidifier and/or heat exchange(heater/cooler) equipment to provide drying fluid for recycle atappropriate desired conditions of temperature and relative humidity.

Thus, drying fluid, including any necessary make-up drying fluid, may beprovided to the drying fluid conditioning assembly 568, or otherwiseprovided to the spray drying system at other appropriate location(s) inthe system, from an appropriate source, and with any appropriatepreconditioning operations being carried out by associated equipment ordevices, as needed to conduct the spray drying operation at the desiredtemperature, pressure, flow rate, composition, and relative humidity.Thus, for example, make-up drying fluid may be provided to theconditioning assembly 568 from a tank, storage vessel, or other source(e.g., the ambient atmosphere, in the case of air as such drying fluid).

As a source of auxiliary drying fluid in the system, a portion of therecycled drying fluid from drying fluid recycle line 554 may be divertedin auxiliary drying fluid feed line 572 containing flow control valve574, to the auxiliary drying fluid conditioning assembly 576. Theauxiliary drying fluid conditioning assembly 576 may be constructed andarranged in any suitable manner, and may be of a same or similarcharacter to the construction and arrangement of the drying fluidconditioning assembly 568. The auxiliary drying fluid conditioningassembly 576 thus conditions the auxiliary drying fluid so that it is atappropriate condition for the use of the auxiliary drying fluid in thesystem.

The conditioned auxiliary drying fluid flows from auxiliary drying fluidconditioning assembly 576 through auxiliary drying fluid feed line 578,from which it flows in auxiliary drying fluid feed line 580 containingpump 582 to the manifold 528, while the remainder of the conditionedauxiliary drying fluid flows in auxiliary drying fluid feed line 578 topump 584, from which it is flowed in auxiliary drying fluid feed line586 to the auxiliary drying fluid central feed line 532, forintroduction in the central region of the interior volume of the spraydryer vessel, as previously described.

It will be recognized that the system shown in FIG. 1 could bealternatively constructed and arranged with the drying fluidconditioning assembly 568 processing both the main flow of drying fluidand the auxiliary drying fluid, without the provision of a separateauxiliary drying fluid conditioning assembly 576, e.g., when the maindrying fluid and auxiliary drying fluid are of a substantially samecharacter with respect to their relevant fluid characteristics. It willalso be recognized that separate flow circulation loops for each of themain drying fluid and auxiliary drying fluid may be provided, when themain drying fluid and auxiliary drying fluid are or comprise differentgases, or are otherwise different in their relevant fluidcharacteristics.

The FIG. 1 system is shown as including a central processor unit (CPU)590 arranged to conduct monitoring and/or control operations in thesystem, and when employed in a controlling aspect, may be employed togenerate control signals for modulation of equipment and/or fluidsconditions, to maintain operation at set point or otherwise desiredoperational conditions. As mentioned, the CPU could be operationallyconnected to the conditioning assemblies 568 and 576, to controlcomponents thereof such as dehumidifiers, thermal controllers, heatexchange equipment, etc.

The CPU 590 is illustratively shown in FIG. 1 as being operativelycoupled by monitoring and/or control signal transmission lines 592, 594,596, 598, 600, 602, and 604 with pump 510, drying fluid conditioningassembly 568, auxiliary drying fluid conditioning assembly 576, flowcontrol valve 574, pump 582, pump 556, and pump 584, respectively.

It will be recognized that the specific arrangement of the CPU shown inFIG. 1 is of an illustrative character, and that the CPU may beotherwise arranged with respect to any components, elements, features,and units of the overall system, including the concentration unit 506,to monitor any suitable operational components, elements, features,units, conditions, and parameters, and/or to control any suitableoperational components, elements, features, units, conditions,parameters, and variables. For such purpose, as regards monitoringcapability, the system may comprise appropriate sensors, detectors,components, elements, features, and units. The signal transmission linesmay be bidirectional signal transmission lines, or may constitutecabling including monitoring signal transmission lines and separatecontrol signal transmission lines.

It will be appreciated that the spray drying system of the presentdisclosure affords arrangements in which the contacting gas, auxiliarycontacting gas, drying fluid, and auxiliary drying fluid, or any two ormore thereof, may have a substantially same composition, temperature,and/or relative humidity, thereby achieving capital equipment andoperating cost efficiencies with corresponding simplification of thesystem requirements. Thus, for example, all of the contacting gas,auxiliary contacting gas, drying fluid, and auxiliary drying fluid maybe air, nitrogen, argon, or other gas from a common gas source, and suchcommon gas may be provided at a substantially same temperature andrelative humidity, so that common thermal conditioning anddehumidification equipment can be employed.

While the disclosure has been set forth herein in reference to specificaspects, features and illustrative embodiments, it will be appreciatedthat the utility of the disclosure is not thus limited, but ratherextends to and encompasses numerous other variations, modifications andalternative embodiments, as will suggest themselves to those of ordinaryskill in the field of the present disclosure, based on the descriptionherein. Correspondingly, the invention as hereinafter claimed isintended to be broadly construed and interpreted, as including all suchvariations, modifications and alternative embodiments, within its spiritand scope.

What is claimed is:
 1. A spray drying process for drying a spray dryableliquid composition to a spray dried powder, wherein the spray dryableliquid composition contains no carrier, the process comprising:providing the spray dryable liquid composition at a solids concentrationnot exceeding 80% by weight, based on total weight of the spray dryableliquid composition, and at a viscosity in a range of from 50 to 28,000mPa-s; atomizing the spray dryable liquid composition to generate anatomized spray of liquid particles of the spray dryable liquidcomposition into a spray drying chamber; applying an electrohydrodynamiccharge to at least one of the spray dryable liquid composition and theatomized spray of liquid particles, for electrohydrodynamic spray dryingof the spray dryable liquid composition; flowing a stream of dryingfluid at a temperature not exceeding 100° C. into the spray dryingchamber for flow through the spray drying chamber, to contact the sprayof liquid particles therein for drying of the liquid particles to formthe spray dried powder; and discharging from the spray drying chambereffluent drying fluid and the spray dried powder dried by contact withthe drying fluid in the spray drying chamber.
 2. The process of claim 1,wherein the electrohydrodynamic charge is applied to the spray dryableliquid composition.
 3. The process of claim 1, wherein theelectrohydrodynamic charge is applied to the atomized spray of liquidparticles.
 4. The process of claim 1, wherein the electrohydrodynamiccharge is applied to the spray dryable liquid composition and to theatomized spray of liquid particles.
 5. The process of claim 1, whereinthe electrohydrodynamic charge is in a range of from 0.25 to 80 kV. 6.The process of claim 1, wherein the electrohydrodynamic charge is in arange of from 0.5 to 75 kV.
 7. The process of claim 1, wherein theelectrohydrodynamic charge is in a range of from 5 to 60 kV.
 8. Theprocess of claim 1, wherein the electrohydrodynamic charge is in a rangeof from 10 to 50 kV.
 9. The process of claim 1, wherein in saidatomizing, the spray dryable liquid composition is sprayed through anelectrohydrodynamic nozzle operatively coupled with a voltage sourcearranged to apply a cyclically switched voltage to the nozzle, for saidapplying an electrohydrodynamic charge to at least one of the spraydryable liquid composition and the atomized spray of liquid particles,for electrohydrodynamic spray drying of the spray dryable liquidcomposition.
 10. The process of claim 1, wherein said atomizing isconducted with an atomizer including an external electrode and agrounded nozzle.
 11. The process of claim 1, wherein said applying anelectrohydrodynamic charge comprises electron beam irradiation of theatomized spray of liquid particles.
 12. The process of claim 1, whereinsaid atomizing is carried out so that the atomized spray of liquidparticles of the spray dryable liquid composition comprise droplets ofthe spray dryable liquid composition having a droplet size in a range offrom 10 to 300 μm.
 13. The process of claim 1, wherein the viscosity ofthe spray dryable liquid composition is in a range of from 50 to 5000mPa-sec.
 14. The process of claim 1, further comprising generatinglocalized turbulence at multiple loci in the spray drying chamber, toenhance drying of the spray dryable liquid composition in the spraydrying chamber.
 15. The process of claim 14, wherein the localizedturbulence is generated by injection of secondary drying fluid into thespray drying chamber.
 16. The process of claim 1, wherein the spraydryable liquid composition has a solids concentration in a range of from50% to 70% by weight, based on total weight of the spray dryable liquidcomposition.
 17. The process of claim 1, wherein the spray dryableliquid composition comprises at least one product material selected fromthe group consisting of food materials, beverage materials, fragrancematerials, pigment materials, flavor materials, pharmaceuticalmaterials, therapeutic materials, medication materials, homeopathicmaterials, biological materials, probiotic materials, constructionmaterials, formulating materials, and mixtures, blends, composites, andcombinations of two or more different materials of the foregoing. 18.The process of claim 1, wherein the spray dryable liquid compositioncomprises at least one product material selected from the groupconsisting of apple juice, tea, coffee, pear juice, amino acids, fruitpurees, pectin, beef broths, gelatin, pharmaceutical products, beetjuice, grape juice, pineapple juice, betacyclodextran, lime juice, skimmilk, carrageenan, liquid egg, sugars, cheese whey, beers, low alcoholbeer, vegetable juices, chicken broth, mango juice, whey protein, citrusjuice, orange juice, and whole milk.
 19. The process of claim 1, whereinthe temperature of the stream of drying fluid flowed into the spraydrying chamber is below at least one of 100° C., 99° C., 98° C., 95° C.,90° C., 85° C., 80° C., 75° C., 70° C., 65° C., 60° C., 55° C., 50° C.,45° C., 40° C., 30° C., 25° C., 22° C., 20° C., 18° C., 16° C., 15° C.,14° C., 13° C., 12° C., 11° C., and 10° C., and said temperature isabove freezing point of the liquid in the spray dryable liquidcomposition.
 20. The process of claim 1, wherein the stream of dryingfluid flowed into the spray drying chamber has a relative humidity in arange in which the lower end point of the range is any one of 10⁻⁴%,10⁻³%, 10⁻²%, 10⁻¹%, 1%, 1.5%, or 2%, and in which the upper end pointof the range is greater than the lower end point of the range, and isany one of 35%, 30%, 20%, 15%, 12%, 10%, 8%, 6%, 5%, 4%, 3%, 2.5%, 2%,1.8%, 1.6%, 1.5%, 1.4%, 1.3%, 1.2%, 1.1%, 1.0%, 0.9%, 0.8%, 0.7%, 0.6%,0.5%, 0.4%, 0.3%, 0.2%, 0.1%, 0.05%, 0.02%, 0.01%, or 0.05%.